Add rust prompt (#261)

Closes #258

bullet-train.zsh-theme

@@ -30,6 +30,7 @@ if [ ! -n "${BULLETTRAIN_PROMPT_ORDER+1}" ]; then
     nvm
     aws
     go
+    rust
     elixir
     git
     hg
@@ -139,6 +140,17 @@ if [ ! -n "${BULLETTRAIN_GO_PREFIX+1}" ]; then
   BULLETTRAIN_GO_PREFIX="go"
 fi
 
+# Rust
+if [ ! -n "${BULLETTRAIN_RUST_BG+1}" ]; then
+  BULLETTRAIN_RUST_BG=black
+fi
+if [ ! -n "${BULLETTRAIN_RUST_FG+1}" ]; then
+  BULLETTRAIN_RUST_FG=white
+fi
+if [ ! -n "${BULLETTRAIN_RUST_PREFIX+1}" ]; then
+  BULLETTRAIN_RUST_PREFIX="🦀"
+fi
+
 # Kubernetes Context
 if [ ! -n "${BULLETTRAIN_KCTX_BG+1}" ]; then
   BULLETTRAIN_KCTX_BG=yellow
@@ -529,6 +541,15 @@ prompt_go() {
   fi
 }
 
+# Rust
+prompt_rust() {
+  if [[ (-f Cargo.toml) ]]; then
+    if command -v rustc > /dev/null 2>&1; then
+      prompt_segment $BULLETTRAIN_RUST_BG $BULLETTRAIN_RUST_FG $BULLETTRAIN_RUST_PREFIX" $(rustc -V version | cut -d' ' -f2)"
+    fi
+  fi
+}
+
 # Kubernetes Context
 prompt_kctx() {
   if [[ ! -n $BULLETTRAIN_KCTX_KCONFIG ]]; then